Heat-exchanging apparatus



' 1,637,276 July 1927' J. FORGAN-POTTS HEAT EXCHANGING APPARATUS Filed Au. 8. 1925 IHIIIINII Inventor Patented July 26, 1927.

PATENT OFFICE;

J'QHN POBGAN-PO'ITS, O1 BRUSSELS, BELGIUM.

HEA'I- IEXCHANGING APPARATUS.

Application fled August 8, 1825, Serial No. 49,075, and in Belgium August 18, 1894.

This invention is for improvements in or relating to heat-exchan 'ng apparatus in which heat is to be transfirred to or from a gas, such as air, and another fluid, such for I example, as steam or hot water. The object of the invention is to provide a construction of apparatus in which the maximum heattransferring surface is contained within the smallest space whilst maintaining at the same time a low resistance to the fiow of the gas. Other advantageous features of the construction as hereinafter described are low first cost, simplicity, accessibility and small number of working parts, and that the apparatus as a unit can work in any position.

According to this invention, there is provided in heat-exchanging apparatus, the

' combination of a casing, a bank of circularly bent tubes disposed in a cylindical formation therein,- heat-transmitting ranes secured on the said tubes andeach inclined to the axis of its tube and also inclined to the axis of the bank oftubes so as to lie in substantially spiral formation about the latter axis, a fan situated at one end of the bank of tubes and delivering air thereto through a casing which is conical about the axis of the fan and an outlet for the air at the other end of the tube-containing casing.

According to another feature of this invention the fan aforesaid is mounted in a chamber adjacent to and coaxial with the tube-containing casing and communicates therewith by an annular opening in the wall l5 separating them.

' 'Accordm to yet another feature of this invention, 51c power unit for the fan may be mounted in such a position, for example, inside the bank of tubes, that the air flows in over it and cools it.

' Preferably, also, the inlet and/or the outlet openings for the air are provided with controlling valves, for the purpose hereinafter set forth; these valves may take the i5 form of louvres arranged to direct the air in its desired path of flow.

In the accompanying drawings, which illustrate diagrammatically two arrangements in accordance with this "invention- 7 Fi ure 1 is an end view partly in section of a eat-exchanging unit,

Figure 2 is a longitudinal section of Figplyand delivery-mains 15, 16 respectively,

so that steam or other heating or cooling .medium can be circulated'throu h the bank of tubes. It will be seen that t e semi-circular bending of the individual tubes between the headers accommodates any expansion or contraction of the tubes which ma take place,-rendering unnecessary the provision of any expansion joints or the like.

The chamber 10 containing the bank of tubes is provided with an end wall 17 in which there is an annular opening 18 by which communication is provided with a second chamber 19 which is coaxial with the chamber 10. Within this chamber 19 there is provided a fan 20 which is of the propeller or axial-flow type; it is arran ed to draw in air' through an opening 21 1n the end wall of the chamber 19 and to deliver it through the opening 18 into the tube-containing chamber 10. This propeller t pe of fan is used on 'account of its abilityo dealing with large volumes of air at a comparatively low delivery pressure for a small amount of power ex enditure. With such fans, however, the eliver is not purely axial, for there is a centri ugal component present. There is therefore provided around the fan a guide or casing 22 which is conical aboutthe axis of the fan with its larger end on the delivery side thereof. This arrange ment provides an easy path of flow of air leaving the fan, so that it is directed into the tube-containing chamber 10 Without shock or violent change of direction, retaining its normal rotary and axial movement.

' or of the. fan, in the same way as the spiral path of flow'of the air, so that the vanes present only an edge to the air-flow and thereby oifer the minimum resistance thereto, some of these vanes being shown at 23 in Fi ure 1.

The fan 20 is conveniently driven y an electric motor 24 which is situated in such a position that it is more or less in the path of fiow of the air from the fan, so that it is effectively cooled thereby. As shown in Figure 2, it is situated inside the bank of tubes 11.

The inlet-openin 21 to the fan-cha1nber 19 is provided wit controlling louvres or shutters 25, and the outlet-opening 26 at the other end of the tube-containing chamber may be similarly provided with shutters 27 so that the flow of air through the apparatus can be controlled in accordance with the requirements. For example, if it is required to be heated to a considerable extent, it can 'be retained in contact with the tubes 12 by partial closing of the shutters27 on theoutlet. The shutters 25 may if desired be so disposed as to direct the enteringa'ir along a path which facilitates its entr into the zone swept by the fan blades, for t e purpose of reducing thepower required in driving the fan.

In the modified arrangement shown in Figure 3, the general construction is the same, but there are shown only two layers of tubes in the bank of tubes 11, and the fan 20 is spaced somewhat further from the annular opening 18 communicatin with the tubecontainmg chamber 10. he fan-motor 24 is situated in the fan-chamber 19, so that the air flows across it to cool it prior to passing through the openin 18 aforesaid. Also, in this case the conica casing 22 is shown as of a more acute angle-of conicity.

It is to be understood that the invention is not limited to the exact shapes and arrange- .ment of parts illustrated, for these are obviously capable of modification within the scope of the present invention, and it will be seen that the invention provides aheat-transferring unit which is capable of a high volumetric eificiency owing to the very low resistance offered to the flow of air through it.

Other advantages which may be noted are that if the fan-blades are made symmetrical, the direction of flow of air may be reversed without complicated reversing dampers, merely by reversing the direction of rotation of the motor. The design, from a commercial point of view, is sim lified, in that a unit can be arranged to eal with largely differing volumes of air simply by varying the number of blades on the fan, and this feature also simplifies the design when the fan speeds are limited b other factors, such for example, as the drivin of the fan by a polyphase motor. The i h volumetric efiiciency of the unit is assiste by the cylindrical formation of the bank of tubes, with the annular opening thereto, since the path of flow of the air is completel symmetrical with respect to the fan. Finally, the unit is complete in itself, and need not neeessaril be arranged with its axis horizontal, for it can be suspended or mounted in any position to suit any particular circumstances. The casing neednot necessaril be cylindrical as to its external form, for if it is desired to attach it to columns or wall-brackets, a rectangular shape may be more convenient.

What I claim as my invention and desire to secure by Letters Patent is 1. In heat-exchanging apparatus the com bination of a casing, a bank of circularlybent tubes disposed in a cylindircal formation therein and occupyin a circumferential space between the interns peri hery of the casing and the internal perip ery of the bank of tubes, which casing has at one end a wall having an annular opening that registers with one end of said circumferential space, and at the other end a wall that closes the other end of the said circumferential space and has an outlet registering with said bank of tubes,afan of the ropeller or axialfiow t pe situated at the rst end wall outside the casing, a second casin which surrounds said fan and is conical a out the axis of rotation of the fan and is arranged to direct a whirlin current oflair delivered by the. fan throug the said annular opening to said circumferential s ace, and heat-transmitting vanes provide on said tubes and inclined each to the axis of its tube and also inclined to the lon 'tudinal axis of the bank of tubes so as to ie in substantially spiral formation about the latter axis, substantially as described.

2. In heat-exchanging apparatus the combination of a casing, a bank of circularlybent tubes disposed in a cylindrical formation therein and occupying a circumferential space between the lnternal periphe of the casing and the internal riphery o the bank of tubes, which casing as at one end a wall having an annular opening that registers with one end of said circumferential space, and at the other end a wall that closes t e other end of the said circumferential space and has an outlet registering with said bank of tubes, a fan of the ropeller or axialflow t pe situated at the rst end wall outside tlze casing, a second casing which surdriving the fan situated, for

rounds said fan and is conical about 'the axis of rotation of the fan and is arranged to direct a whirling current of air delivered by the fan through the said annular opening to said circumferential space, a ower unit for the purpose described, at the same side of the fan as the said bank of tubes is situated, and heattransmitting vanes provided on said tubes and inclined each to the axis of its tube and also inclined to the lon itudinal axis of the bank of tubes, substant ally as described.

In testimony whereof I aflix my signature.

JOHN FORGAN-POTTS. 

